. Botany for agricultural students . Botany. 314 THALLOPHYTES special cells and often on different plants. Also in the higher forms, the introduction of a case around the oospore, and a new structural stage between fertilization and the formation of new plants, suggests a relationship to the higher plants. On the other hand, the simpler forms resemble some of the Protococcales from which the Confervales have probably been evolved. Conjugating Algae (Conjugales).—This group is so named because of the peculiar conjugating habit, in which the contents of two cells fuse to form zygospores. Some ar
. Botany for agricultural students . Botany. 314 THALLOPHYTES special cells and often on different plants. Also in the higher forms, the introduction of a case around the oospore, and a new structural stage between fertilization and the formation of new plants, suggests a relationship to the higher plants. On the other hand, the simpler forms resemble some of the Protococcales from which the Confervales have probably been evolved. Conjugating Algae (Conjugales).—This group is so named because of the peculiar conjugating habit, in which the contents of two cells fuse to form zygospores. Some are unicellular but many are filamentous. They include Spirogyra and others that. Fig. 270. — Desmids. a and 6, two ccmmon species of Desmids highly magnified; at the right of c, a Desmid dividing, and at the left of c, each daughter cell resulting from the division developing a new half; at d, the pro- toplasts of two Desmids are escaping and conjugating. Redrawn from Curtis. are very common nearly everywhere in fresh water. They are free floating, and the filamentous forms often form extensive floating mats, which are buoyed up by the oxygen entangled among the filaments. Some, owing to the shape and arrange- ment of their chloroplasts, are attractive plants under the micro- scope. One peculiar feature of the group is that, although the plants are aquatic, there are no ciliated cells of any kind. Desmids. — The simplest of the Conjugales are the Desmids, which are unicellular floating plants that exhibit a variety of shapes and some are extremely beautiful (Fig. 270). They are. Please note that these images are extracted from scanned page images that may have been digitally enhanced for readability - coloration and appearance of these illustrations may not perfectly resemble the original Martin, John N. (John Nathan), b. 1875. New York : John Wiley & Sons, Inc.
Size: 1790px × 1395px
Photo credit: © Central Historic Books / Alamy / Afripics
License: Licensed
Model Released: No
Keywords: ., bookcentury1900, bookdecade1910, booksubjectbotany, bookyear1919
